While Battlefield 3 is being targeted towards the high-end PC market, developer DICE has made the decision to omit modding tools for the upcoming FPS. “As of now, we are not going to make any modding tools,” DICE's Patrick Söderlund told GameStar (via PC Mag). "If you look at the Frostbite engine, and how complex it is, it’s going to be very difficult for people to mod the game, because of the nature of the set up of levels, of the destruction and all those things... it’s quite tricky. So we think it’s going to be too big of a challenge for people to make a mod."
The Frostbite engine has been largely praised for producing such impressive visuals for Battlefield 3. Undoubtedly, the enthusiastic modding community would love to get hands on that tech--and it's likely they will, regardless of a release of an officially sanctioned mod tool. For example, the community eventually released new maps for DICE's Mirror's Edge. (Although that title used Unreal Engine 3.) Söderlund's statement seems like an invitation for the community to open up the game.
In an interview with Edge, lead multiplayer designer Lars Gustavsson said "we could probably do a ten base Rush map! It’s definitely doable." He added, "there’s nothing preventing us, if people had the time and the will." That sounds like a challenge for the dedicated mod community to tackle, doesn't it?